Turbine posted an announcement that the game servers will be restarted tomorrow:

The LOTRO game servers will be brought down for a restart on Thursday, May 8 from 9:00AM - 10:00AM Eastern (-4 GMT)* in preparation for Welcome Back Weekend. Thanks for your patience, and we'll have the servers back online as soon as possible!

* And as always, apologies to our Oceanic players for hitting their prime time!